Granted Patent
Utility
US 5,422,939 · App. 08/102,325
Parallel off-hook detection for both line-available and phone pick-up detection
Inventors:
Richard Alan Kramer, Scott C. Swanson
Patented Case
View Patent ↗
Granted: Jun 6, 1995
Filed: Aug 5, 1993
Inventors
Richard Alan Kramer
Scott C. Swanson
Assignee (at issue)
Schlumberger Industires, S.A.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.